Updating and Structure in Non-Monotonic Theories (PhD Dissertation 1992, Stanford & IBM)

Pragmatic reasoning often involves conflict about beliefs with some degree of plausibility, e.g., overridable rules (defaults). However, conflict (i.e., logical non-monotonicity) can require impractical (i.e., intractable) computational effort. We attack the problem at a logical level, choosing the circumscription formalism as our vehicle of analysis for its mathematical convenience and expressive power. We give a new divide-and-conquer strategy for coping with the challenges of scale, based on new concepts of decomposition and of truth maintenance. We show new general- and special-case results about how to localize updating and belief revision, forward and backward inferencing, and specification. Many of the special cases can be recognized syntactically, and thus are computationally tractable. In addition, we employ a new, more-general concept of prioritization.

By: Benjamin N. Grosof

Published in: RC20683 in 1997

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